Kosmos 2495 Re-Entry

A Russian film-return reconnaissance satellite or a component thereof may have re-entered the atmosphere over the United States last week, witness reports and orbital data suggests.

Contrary to reports from U.S. observers, the Russian Ministry of Defence claims that 'no violations or deviations' from standard procedures have taken place and no spacecraft re-entered over the U.S. In support of the Russian claims, videos showing the apparently successful landing of the Kosmos-2495 film return capsule surfaced on the Internet.

However, taking previous missions and orbital data collected from last week's incident as evidence, it will be shown that a part of the Kosmos satellite was responsible for the fireball seen over parts of America on September 2nd.

Fireball over the U.S.

Credit: Cloudbait Observatory / Spaceflight101

Animation of frames acquired by the Cloudbait Observatory at the DMNS Location clearly showing the south-to-north motion of the object

A bright, long-lasting fireball was seen in the skies over Colorado and Wyoming and possibly as far as New Mexico, South Dakota and southern Montana. The event occurred just after 10:30 p.m. local time on September 2 (4:30 UTC on the 3rd). Over 30 witness reports of the event were published by the American Meteor Society. The fireball made local news last week, however, no photos or video of the event were published immediately after the event. A number of witnesses, including experienced sky-watchers reported that the object was moving much slower than a usual fireball, some immediately conclude that what they were observing was the re-entry of a piece of space debris. Reports submitted to AMS are in good agreement on the time of the event and most observers were able to track the object for a considerable period of time which supports the theory of a decaying satellite. Some witnesses were able to see the re-entering object for thirty seconds or longer, reporting that the object was moving slowly. All witness reports agree on the movement of the object from south to north which is illustrated in the observer map that shows the final-viewing direction reported by experienced witnesses, lining up in a northerly direction. Fragmentation and an increasingly longer trail were reported by the majority of witnesses, describing that the object first split in two fragments, one smaller and one bigger before a complete break-up of the objects followed by a slow fade-out of the glowing fragments.

The longevity of the event and the low velocity of the object suggests that it was indeed a re-entering spacecraft - most likely a satellite flying in a highly inclined orbit, based on the observed track from south to north. However, the possibility of a slow meteor, entering the atmosphere at a speed of 12km/s could not be ruled out based on witness reports alone.

Confirmed Observations

Image: Google Earth/Spaceflight101/AMS

Reported observations of the Fireball from New Mexico, Colorado, Wyoming, South Dakota and Montana (Final viewing directions in red)

Dan B. observed comet Jacques from Alamogordo, New Mexico using image stabilized binoculars when noticing a bright object entering the field of view.In his report,he described the object to be orange in color, tumbling at a rate of one revolution per second with a vivid smoke trail.

Notably, he also states that the object was much slower than a meteorite. Very little fragmentation was seen from his perspective as the object flew from zenith to the horizon.Looking at the map of witness reports, this observation lines up perfectly with observations made from Colorado who picked up the object after passing over Dan B.'s location - this confirms that he observed the extremely rare sight of a satellite in the early stages of re-entry - showing a trail of smoke without experiencing break-up yet. Also located in New Mexico, Thomas Ashcraft captured the event via his sky camera and radio antennas. The video shows the object changing brightness and the radio reflection also fluctuated, indicating that the object was tumbling at the time it was passing over New Mexico, most likely already in the initial stages of re-entry with plasma building up around the object.

Image: Google Earth/Spaceflight101/AMS

Dan B.(New Mexico) viewing direction & Kosmos 2495 Ground Track

The report of discernible tumbling ahead of re-entry, the duration of the visible entry process and length of the ground track with confirmed observations indicates that the object was of considerable size.

Object over New Mexico during the early Stages of Re-Entry (Credit: Thomas Ashcraft)

Most likely already immersed in plasma, the tumbling object experienced the first stages of re-entry over New Mexico.

One very important item for further analysis is the timing of the event. Witness reports submitted to AMS show event times from 4:30 to 4:40 UTC which is quite a large margin that would make further analysis difficult. Luckily, the Colorado All-Sky Camera Network Station at the Denver Museum of Nature and Science and at Cloudbait Observatory captured the event providing a precise timing. The animation above shows the re-entering object as captured at DMNS with time stamps of 4:34:04 to 4:43:26 UTC. However, it has become known that the calibration of this camera for both time and altitude is not correct.The timing data from Cloudbait Observatory is precise to the second and shows the event from 4:32:13 to 4:32:41 UTC. The time of maximum elevation was 4:32:25 UTC.

Satellite Re-Entry

With all indications pointing to a re-entering spacecraft as the cause of the fireball observed in the night of September 2, one can turn to re-entry data provided by U.S. Space Surveillance. For September 2 and 3, there are only four decay messages:

a small piece of Fengyun 1C Satellite Debris

the 1U INVADER CubeSat measuring 10 by 10 by 10 centimeters

the Chinese Yaogan-5 satellite with a mass of around two metric tons

the Russian Kosmos-2495 satellite that is marked as an elective re-entry, not caused by natural orbital decay

The first two objects, the debris and CubeSat, can be immediately ruled out since the magnitude of the observed event was caused by an object much greater in size and mass. The re-entry of Yaogan-5 has been observed by U.S. Space Surveillance providing a re-entry time of 20:30 UTC +/-1 minute at a location over the southern Indian Ocean. This only leaves the Kosmos-2495 satellite, a Russian film-return satellite delivered to orbit on May 6, 2014 atop a Soyuz rocket launching from the Plesetsk Cosmodrome. Plotting the final orbital data of the four potential candidate spacecraft and propagating to the time of the observed fireball shows that only Kosmos 2495 can be responsible for the U.S. event.

Positions of candidate Spacecraft - 4:35 UTC, Sep 3, 2014

Image: Spaceflight101/JSatTrak

Image: TsSKB Progress

Yantar Photoreconnaissance Satellite

A relic of the soviet era, the Kobalt-M satellites originate in the Yantar photoreconnaissance project that dates back to 1964. Kosmos 2495 was likely the second to last of its kind to fly into space since Russia has started the operation of electro-optical satellites that downlink acquired imagery to the ground instead of returning physical film to Earth.

Operating from a very low orbit of around 200 Kilometers, the Kobalt satellite can obtain high-resolution imagery of ground targets.Kobalt-M satellites measure 6.3 meters in length and 2.7m in diameter with a launch mass of 6,600 Kilograms, including a 900kg fuel load that is expended during the mission to maintain the satellite's extremely low operating orbit. The satellite consists of a Service Module, an Instrument Module and a Payload Module that carries the camera and main film capsule as well as two smaller film capsules.To return film to the ground, the satellite uses two small return capsules that are separated from the satellite and land in Russia. A third capsule is part of the cone-shaped Payload Module that returns at the end of the mission when the spacecraft performs a targeted re-entry to land in a pre-determined location within Russian territory.

Looking at the last known orbital parameters from September 2 at 17:11:55 UTC, Kosmos 2495 was in an orbit of 205 by 250 Kilometers inclined 81.4 degrees. This data confirms two items of interest - the satellite was still in orbit on September 2nd but re-entered before September 3rd 7:48 UTC which is the time stamp of the Kosmos 2495 decay message provided by U.S. Space Surveillance.

Second and most importantly, the satellite was in an orbit that was not close to a natural, untargeted decay. (For reference, the propagation software SatEvo shows that the orbit had an approximate lifetime on the order of two weeks.) This indicates that the satellite's re-entry was the result of a propulsive event.

Image: Orbitron

Kosmos 2495 Ground Track

Plotting the satellite's ground track for the night of September 2nd shows that the Kosmos 2495 satellite made a pass over New Mexico, Colorado and Wyoming at the reported time of the fireball.

Both the ground track and the timing of the event are in good agreement with the last orbital data of Kosmos 2495 that would have passed over the border between New Mexico & Colorado at 4:36:25 UTC if it had still been in the orbit it was observed in at the 17:11 Epoch. Taking the Colorado Allsky reference time of 4:32:25 UTC (passing directly west of Cloudbait at highest elevation) and comparing it with the last known orbit of Kosmos-2945 that would have passed that position at 4:36:51 UTC shows that the satellite arrived ~266 seconds early.

An early arrival of approximately three to five minutes is plausible as the result of the reduction in orbital period of an decaying object.

Observations & Kosmos 2495 Ground Track

Following the re-entry event, a Doppler Radar in Cheyenne, Wyoming tracked the 150-Kilometer long debris cloud left behind by the object for half an hour. The cloud is located approximately 118 Kilometers east of the satellite ground track which can be explained by the early arrival time of the satellite. The orbital plane of the satellite is inertial while Earth rotates underneath it.

At 39.6°N, a given point is moving at a speed of 0.355km/s as Earth rotates from west to east. This accounts for 94.5 Kilometers of the displacement seen in the debris cloud. The other contributing factor that is known to influence an object's trajectory through the atmosphere is cross wind. For September 2nd around the time of re-entry, winds in the upper atmosphere were coming straight from the West at up to 31knots over 11,000 feet accounting for the rest of the cross track error seen in the debris path compared with the orbital path.

Doppler Images showing the Debris Cloud

Credit: Björn Gimle/Rob Matson

Image: NOAA

Doppler image of the debris cloud well after the event, located east of the satellite ground track.

Definitive Velocity Measurement

An essential piece of information was provided to Dr Marco Langbroek by Dr Bill Cooke of the Meteoroid Environments Office at NASA's Marshall Space Flight Center: the object entered the atmosphere with a speed of 7.69 +/-0.07 km/s as determined by cameras located in New Mexico. This velocity measurement confirms without any doubt that the object was an artificial satellite or component thereof originating in Low Earth Orbit. With a very close fit in location, timing and speed it can be said with nearly absolute certainty that the re-entry observed over the U.S. on September 2 was related to the Kosmos-2495 satellite considering that there are no other re-entry candidates on record.

It was reported that the re-entry occurred at 18:14 UTC on September 2 which matches that day's landing opportunity in the normal recovery area as seen on the orbital ground track that shows the satellite passing from south to north over Saudi Arabia, the Persian Gulf, Iran, the Caspian Sea, the Atyrau and West Kazakhstan regions before heading over the Russian border into the Orenburg Region. Observations along the ground track are a close match and the timing is correct as well. Calculations using the last orbital data would suggest a start of re-entry around 18:16 UTC and landing approximately 13 minutes later. The videos showing the event were all uploaded on September 2nd and 3rd. It can be ruled out that the videos were shot a day earlier when the Foton-M #4 satellite made its return to Earth on a similar trajectory since that took place during daylight hours. The videos show a small bright object flying well in front of a larger disintegrating object - indicative of the re-entry vehicle on a ballistic entry path pulling out in front of the Service Module of the satellite that broke up in the upper atmosphere. The Service Module of the Kobalt satellite houses the main propulsion system that is presumably used for all orbital maneuvers and the deorbit burn before the Service Module is separated from the cone-shaped re-entry vehicle that itself is equipped with eight thrusters for attitude control during re-entry leading up to a landing under a parachute cushioned by soft landing engines to safely return the film and the Zhemchug-4 optical imaging system. The videos, location and timing of the event are a very good confirmation that the Kosmos-2495 satellite returned to Earth as planned and did not re-enter over the U.S. - at least not in its entirety.

Credit: YouTube User Sapargaliev Aibar

Re-Entering object over Kazakhstan, possibly the film capsule flying in front of the disintegrating Service Module

Re-Entry data shows no match for any spacecraft re-entries on September 2/3 over America, only leaving Kosmos 2495 that apparently touched down in Russia ten hours before the fireball was spotted over Colorado. But there is a connection!

Connecting the Dots by looking into the Past

Kobalt-M satellites and their predecessors known as Kobalt, Oktan, Feniks and Kometa are all based on the Yantar satellite bus that has changed very little since the mid-1970s except for upgrades made to the imaging payload. All these satellites are known to separate a number of debris over the course of their final days or hours in orbit. The origin of these pieces seems clear when looking at the design of the satellites: the OSA (Payload Module) includes the optical imaging system, film handling and storage systems, re-entry and landing support systems (attitude thrusters, parachutes, soft landing engines, heat shield, onboard computer), a deployable sun shade and communication antennas. The sunshade is needed to avoid direct sunlight entering the optics and as stray light protection while the need for mounting communication antennas in front of the satellite arises due to the satellite pointing its aperture towards Earth for the majority of the mission. To ensure a safe and predictable re-entry, the sun shield, antennas and any other protruding structures are jettisoned as part of the preparatory steps executed at the end of the satellite's mission which also include the retraction of the camera system to protect it during entry. It is also reported that the satellite may jettison is solar arrays before conducting the deorbit burn.

The debris generated by the Yantar satellites are released into a very low orbit just over 200 Kilometers. Due to their large size and low mass, they experience a rapid decay caused by drag in the Low Earth Orbit environment. In many cases over the past years, the debris were cataloged by U.S. Space Surveillance, but in a number of instances no debris were tracked at all, not because they were not present, but more likely due to their re-entry before they could be cataloged.

Photo: TsSKB Progress

Looking back at the nine Kobalt-M satellites launched between 2004 and 2014 shows that five of these missions were associated with tracked debris. Looking further back to 1990, at least nine Yantar missions created debris that could be tracked.

The number of tracked debris varies between one and three. Usually, only a few orbital element sets are issued for each piece which confirms their quick orbital decay and the likelihood that some debris may not be detected at all.

Although the Kosmos 2495 mission did not show any tracked debris, data from previous Kobalt-M missions may be a good indicator for the average orbital lifetime of the debris to allow an assessment of the probability of a Kosmos 2495 debris making it to the U.S. to cause the September 2 fireball.

Satellite

Flight
Duration

Last known
Orbit

# Debris

Kosmos
2480

05/17/12-09/24/12

197 x 269km,
81.3°

-

Kosmos
2472

06/27/11-10/24/11

201 x 242km,
81.4°

-

Kosmos
2462

04/10/10-07/21/10

180 x 270km,
67.2°

3

Kosmos
2450

04/29/09-07/27/09

180 x 282km,
67.1°

-

Kosmos
2445

11/14/08-02/23/09

188 x 277km,
67.2°

2

Kosmos
2427

06/07/07-08/23/07

177 x 347km,
67.1°

2

Kosmos
2420

05/03/06-07/19/06

169 x 270km,
67.1°

2

Kosmos
2410

09/24/04-01/09/05

183 x 288km,
67.1°

2

The Kosmos 2462 mission in 2010 is the most recent Kobalt-M flight with tracked debris, but no orbital elements are available for the three debris pieces that were cataloged. The most recent mission that enables us to do some orbital forensics is Kosmos 2445 that launched on November 14, 2008 and re-entered on February 23, 2009 after a duration of 101 days. The Kosmos 2445 satellite, also known by its International Designator 2008-058A, separated two objects that were identified as 058C and 058D. Three Elsets were issued for 058C while four were provided for 058D. The very first orbital data for both debris has an Epoch of 17:31 UTC on February 23, 2009. Propagating these Elsets into the past with the closest data for Kosmos 2445 yields an approximate separation time for the objects at around 9:30 UTC, being released into an orbit of around 188 by 277. Based on the available data, the separation time should be given with a window of at least two orbits.Inputting the final Elset for each debris into the Orbital Evolution Software SatEvo can yield an approximate decay time for the objects. The final Elset for 058C is from 00:26 UTC on February 24, 2009 and provides an estimated decay time of 1:48 UTC. The last Epoch for 058D is 0:25 UTC and the decay is estimated at 1:33 UTC.

Image: Spaceflight101/JSatTrak

Image: Spaceflight101/JSatTrak

Estimated Location of Debris 058C (left) and 058D (right) at orbital decay in a position ahead of the predicted Kosmos 2445 position. Also note the east-west displacement of the orbit.

The debris separated by Kosmos 2445 had an approximate orbital lifetime of ~12 hours. Taking into account the landing time of the satellite estimated at 16:15 UTC on February 23, the two debris outlasted the satellite by 9.5 hours.

The case of Kosmos 2427 is not suitable for comparison with Kosmos 2495 due to different orbits being used by the missions. On its last day of existence, Kosmos 2427 produced two debris objects that were released into an orbit of 180 by 350 Kilometers before Kosmos 2427 returned to Earth on August 22, 2007 at approximately 18:00 UTC based on witness reports. The two debris had an orbital life of 15 to 47 hours.

Kosmos 2420 flew from May 3 to July 19, 2006 (76 days) and also generated two debris shortly before returning to Earth. The first object, 2007-017D, separated at some point in the two orbits leading up to the deorbit burn for a landing of the spacecraft at approximately 17 UTC on July 19. The separation orbit was approximately 170 by 270 Kilometers. It can be assumed that the second object, 017E, separated around that time as well, but only having one Elset makes a calculation difficult. Using SatEvo to estimate the time of orbital decay shows that 017D re-entered about 20 hours after the landing of Kosmos 2420 and 017E outlasted the satellite by around 12 hours.

The very first Kobalt-M mission lasted 107 days from September 24, 2004 to January 9, 2005. In this case, two debris were released into an 190 by 280-Kilometer orbit around 9 UTC on January 8, one full day before landing that would have occurred shortly before 8 UTC on January 9. The first of the debris, 2004-038C re-entered on January 8, 19:45 +/-1 minute based on actual tracking data provided by U.S. Space Surveillance giving the object an orbital life of around 11 hours or 7 orbits around Earth. Tracking data for 2004-038D shows re-entry taking place at 21:25 UTC +/- 50 minutes meaning that this object endured up to 14 hours in its orbit.

From this look at past missions that created trackable debris it becomes evident that all Kobalt-M debris are subject to a rapid natural decay taking place 12 to 48 hours after their separation, depending on their initial orbit. This also confirms, that for a typical case with separation in the orbits just prior to landing, the debris will remain in orbit for several hours after the landing of the main Kosmos satellite. From an orbital standpoint, the Kosmos 2410 and 2445 missions are the closest to Kosmos 2495 and the endurance of the debris generated during these missions is in line with the debris re-entering over the United States ten hour after the landing of Kosmos 2495 which assumes a debris jettison in the last three orbits of the mission.

Previous Kobalt-M missions that provided sufficient tracking data for a calculation of the area to mass ratio of the jettisoned objects show a good agreement with an A/m ratio that varies 0.063 to 0.077m²/kg. To calculate the ballistics for the Kosmos 2495 mission, this value is used in a simulation of the approximate separation orbit of 205 by 250 Kilometers taking into account atmospheric conditions through inputs of solar flux and geomagnetic index. Modeling these conditions provides an orbital lifetime of 13.656 hours after the release of the object. From looking at previous missions, it is known that the objects separate shortly before re-entry, perhaps within that last two or three orbits of the mission. For Kosmos 2495, this would lead to an approximate jettison time of around 14:50 UTC, three and a half hours before the observed landing in Orenburg, Russia. Leading up to its orbital decay, the object began to tumble which can be seen in Thomas Ashcraft's video from Lamy, New Mexico. At the time of the video, the object should have been in darkness, still several hundred Kilometers away from entering daylight. It being visible in the video is a good indication for the early stages of re-entry beginning around 100 Kilometers in altitude (depending on atmospheric conditions) when plasma begins building up on the object prior to the onset of fragmentation around 80 Kilometers in altitude.Passing out of range from the New Mexico observers, the debris began to break apart over Colorado as seen by the Allsky Cameras and dozens of observers. The debris cloud observed on radar lines up perfectly with the adjusted ground track to account for Earth's rotation underneath the inertial orbital plane of the object. Its early arrival time relative to the Kosmos 2495 orbital prediction is in agreement with simulations run for previous Kobalt mission that showed timing offsets between four and seven minutes, depending on the longevity of the debris objects in their orbits.

Image: Spaceflight101/JSatTrak

Orbital propagation of a simulated object separating from Kosmos 2495 at 14:50 UTC up to its decay shows it heading out four minutes ahead of the Kosmos 2495 prediction at the time of decay.

Image: Spaceflight101/JSatTrak

It is unlikely that any pieces of the object survived re-entry and reached the ground, given the structure of the components that are jettisoned from the Kobalt satellites (solar arrays, sun shade, antenna).

In summary, the fireball observed over the United States in the night of September 2 can be connected to the return of the Kosmos 2495 satellite with a very high degree of certainty, based on the data presented on this page. It was not Kosmos 2495 itself that re-entered over the U.S. but an object released from the satellite in the hours leading up to its return to Earth. This is supported by ballistics data from tracked debris released on previous Kobalt-M missions.

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